It is known that on assembly such cells present highly variable times for absorption of electrolyte by their electrodes because of the way in which air is imprisoned by the electrolyte within the electrodes. To ensure that the electrolyte is completely is absorbed, it therefore becomes necessary to lengthen filling times, but even so it often happens that filling is stopped prematurely because apparent saturation has been observed. This gives rise to pollution of the connections and of the closure of the cell, and also external pollution if excess non-absorbed electrolyte should overflow from the enclosure of the cell. Furthermore, if fresh electrolyte drops onto non-absorbed electrolyte, then splashes occur that can pollute the sealing fillet and the outside surface of the enclosure.